NCT02492451.

Methods	Randomised controlled trial, 3 groups, set in Zeynep Kamil Maternity and Pediatric Research and Training Hospital, Turkey June 2015 to December 2015 Number of participants randomised: 118 (study authors intended to enrol 200 participants, but the study was prematurely terminated due to "problems in recruitment") Number of participants analysed: 118
Participants	Inclusion criteria: patients undergoing intrauterine insemination (IUI) with gonadotropin stimulation; bilateral patent fallopian tubes as assessed by hysterosalpingography or laparoscopy; total progressive sperm count > 5 million after semen preparation for IUI Exclusion criteria: endocrinological or metabolic disorder; uterine factor; pelvic inflammatory disease; basal follicle‐stimulating hormone (FSH) level > 15 IU/mL; body mass index (BMI) ≥ 35 kg/m²; age ≥ 40 and < 18 years Cause of infertility: not reported
Interventions	Intervention group 1: endometrial scratch on Cycle day 21 to 24 of the spontaneous menstrual cycle preceding the IUI cycle Intervention group 2: vaginal progesterone gel (Crinone 8%) administered as luteal phase support from the second day after IUI until the day of the pregnancy test, and if pregnant, continued until 12 weeks of pregnancy Control group: no intervention All groups: IUI stimulated with gonadotropin Degree of endometrial injury: pipelle Timing of endometrial injury: in the luteal phase on Cycle day 21 to 24 of the cycle preceding the IUI cycle Study length: not reported Type of conception: IUI
Outcomes	Reported in the trial registry: Clinical pregnancy rate (not defined) Ongoing pregnancy rate (not defined)
Notes	Funding source: not reported Conflicts of interest: not reported Trial registration: NCT02492451 This study is awaiting classification, as study results are not published. Study results are shown under the tab 'Study results' at the trial registry, but these results could not be confirmed. Author correspondence was undertaken, but we did not receive a response